Door knob attachment



FIG. 1 is a front top perspective view of a door knob attachment showing my new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a back view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

Those portions of the figures that are presented in broken lines merely illustrate the environment of the design and are not part of the claimed design. 

CLAIM The ornamental design for a door knob attachment, as shown and described. 